<style>
    :not(:defined) {
        display: none;
    }

    /* Force the scroll bar to appear so we see it hide when overlay opens. */
    body::-webkit-scrollbar {
        background: lightgray;
    }

    body::-webkit-scrollbar-thumb {
        background: darkgray;
    }
    #container{
        color: #000;
        font-size: 14px;
        width: 850px;
        height: 450px;
        text-align: center;
        padding: 10px;
        background: #B0B0B0;
        border: 1px outset #777
    }


    #top{
        background: #B0B0B0;
        text-align: center; 
        text-align: center;
        font-size: 16px;
        font-weight: bold;
    }
   
   





    
</style>
<elix-dialog id="svg_createment" aria-label="Sample dialog" closed>
    <div id="top"><h>图形预览</h></div>
     <div id="container">
      
     </div>
   
    
</elix-dialog>